One of the arguments commonly deployed by opponents of equal marriage is that the existence of civil partnerships for same-sex couples means its introduction is unnecessary. Conservative MP Edward Leigh, for instance, has argued: "Same-sex couples already have all the rights of marriage in the form of civil partnership. Why must they also have the language of marriage?" Former Tory defence minister Gerald Howarth has commented: "some of my best friends are in civil partnerships, which is fine, but I think it would be a step too far to suggest that this is marriage", while Environment Secretary Owen Paterson, who is expected to vote against equal marriage today, has said that the government is "rightly committed to advancing equality for lesbian, gay, bisexual and transgender people and has already taken action to do so by allowing those religious premises that wish to carry out civil partnerships to do so".

But what none of these three will tell you is that they all voted against civil partnerships when Labour introduced them in 2004. MPs are, of course, free to change their minds and we should praise them when they do. But it's hard not to see their new-found support for civil partnerships as a cynical attempt to prevent the equalisation of marriage. Gay couples might already have a means of formalising their relationships but they wouldn't if Paterson, Leigh and Howarth had had their way in 2004. So, for the record, here are the 38 Conservative MPs who voted against civil partnerships, including two serving cabinet ministers (Paterson and Transport Secretary Patrick McLoughlin) and the two Labour MPs who did. Seventeen have since resigned or lost their seats.

Conservative MPs who voted against civil partnerships

David Amess (Southend West)

James Arbuthnot (North East Hampshire)

Paul Beresford (Mole Valley)

Julian Brazier (Canterbury)

Christopher Chope (Christchurch)

Patrick Cormack (South Staffordshire. Stood down in 2010)

Quentin Davis (Grantham and Stamford. Defected to Labour in 2007 and stood down in 2010)

Adrian Flook (Taunton. Stood down in 2010)

Mark Francois (Rayleigh and Wickford)

Roger Gale (North Thanet)

John Gummer (Suffolk Coastal. Stood down in 2010)

Nick Hawkins (Surrey Heath. Stood down in 2005)

John Hayes (Current energy minister and MP for South Holland the Deepings)